Vein thrombosis is a medical condition wherein a blood clot, or thrombus, has formed inside a vein. Such a clot often develops in the calves, legs, or lower abdomen, but can also affect other vasculature in the body. The clot may partially or completely block bodily fluid flow and may break off and travel through the bloodstream (as an embolus). Commonly, clots are caused by a pooling of blood in the vein, often when an individual is bed-ridden for an abnormally long duration of time, for example, when resting following surgery or suffering from a debilitating illness, such as a heart attack or traumatic injury. However, there are other situations that may cause the formation of a blood clot.
Vein thrombosis is a serious problem because of the danger that the clot may break off and travel through the bloodstream to the lungs, causing a pulmonary embolism. This is similar to a blockage of the blood supply to the lungs that causes severe hypoxia and cardiac failure, which frequently result in death. For many patients, anti-coagulant drug therapies may be sufficient to dissipate the clots. For example, patients may be treated with anticoagulants such as heparin and with thrombolytic agents such as streptokinase.
Unfortunately, some patients may not respond to such drug therapy or may not tolerate such therapy. Also, there may be other reasons why an anticoagulant is not desirable. For example, patients may have an acute sensitivity to heparin or may suffer from prolonged internal and/or external bleeding as a result of such drug therapies. Also, such drug therapies simply may be ineffective in preventing recurrent pulmonary emboli. In such circumstances, surgical procedures may be necessary to reduce the likelihood of pulmonary emboli. Mechanical interruption of the inferior vena cava typically presents an effective method of preventing of pulmonary embolisms.
Vena cava filters are devices which are implanted in the inferior vena cava, providing a mechanical barrier to undesirable particulates. The filters may be used to filter peripheral venous blood clots and/or other particulates, which if remaining in the blood stream can migrate in the pulmonary artery or one of its branches and cause harm. However, vena cava filters may be improved.
Therefore, methods and apparatus for filtering a body lumen may be useful.
It should be noted that the figures are not drawn to scale and that elements of similar structures or functions are generally represented by like reference numerals for illustrative purposes throughout the figures. It also should be noted that the figures are only intended to facilitate the description of embodiments of the present invention.